Information About PIM

PIM, which is used between multicast-capable routers, advertises group membership across a routing domain by constructing multicast distribution trees. PIM builds shared distribution trees on which packets from multiple sources are forwarded, as well as source distribution trees on which packets from a single source are forwarded. For more information about multicast, see the "Information About Multicast" section.

Cisco NX-OS supports PIM sparse mode for IPv4 networks (PIM). (In PIM sparse mode, multicast traffic is sent only to locations of the network that specifically request it.) You can configure PIM to run simultaneously on a router. You can use PIM global parameters to configure rendezvous points (RPs), message packet filtering, and statistics. You can use PIM interface parameters to enable multicast, identify PIM borders, set the PIM hello message interval, and set the designated router (DR) priority. For more information, see the "Configuring PIM Sparse Mode" section.

Note Cisco NX-OS does not support PIM dense mode.

In Cisco NX-OS, multicast is enabled only after you enable the PIM feature on each router and then enable PIM sparse mode on each interface that you want to participate in multicast. You can configure PIM for an IPv4 network. In an IPv4 network, if you have not already enabled IGMP on the router, PIM enables it automatically. For information about configuring IGMP, see Chapter 3 "Configuring IGMP".

You use the PIM global configuration parameters to configure the range of multicast group addresses to be handled by each of the two distribution modes:

•Any Source Multicast (ASM) provides discovery of multicast sources. It builds a shared tree between sources and receivers of a multicast group and supports switching over to a source tree when a new receiver is added to a group. ASM mode requires that you configure an RP.

•Single Source Multicast (SSM) builds a source tree originating at the designated router on the LAN segment that receives a request to join a multicast source. SSM mode does not require you to configure RPs. Source discovery must be accomplished through other means.

You can combine the modes to cover different ranges of group addresses. For more information, see the "Configuring PIM" section.

For more information about PIM sparse mode and shared distribution trees used by the ASM mode, see RFC 4601.

Note Multicast equal-cost multipathing (ECMP) is on by default in the Cisco NX-OS for the Cisco Nexus 3000 Series switches; you cannot turn ECMP off. If multiple paths exist for a prefix, PIM selects the path with the lowest administrative distance in the routing table. Cisco NX-OS supports up to 16 paths to a destination.

Hello Messages

The PIM process begins when the router establishes PIM neighbor adjacencies by sending PIM hello messages to the multicast address 224.0.0.13. Hello messages are sent periodically at the interval of 30 seconds. When all neighbors have replied, then the PIM software chooses the router with the highest priority in each LAN segment as the designated router (DR). The DR priority is based on a DR priority value in the PIM hello message. If the DR priority value is not supplied by all routers, or the priorities match, the highest IP address is used to elect the DR.

Caution If you change the PIM hello interval to a lower value, we recommend that you ensure it is appropriate for your network environment.

The hello message also contains a hold-time value, which is typically 3.5 times the hello interval. If this hold time expires without a subsequent hello message from its neighbor, the switch detects a PIM failure on that link.

For added security, you can configure an MD5 hash value that the PIM software uses to authenticate PIM hello messages with PIM neighbors.

Note If PIM is disabled on the switch, the IGMP snooping software processes the PIM hello messages.

Join-Prune Messages

When the DR receives an IGMP membership report message from a receiver for a new group or source, the DR creates a tree to connect the receiver to the source by sending a PIM join message out the interface toward the rendezvous point (ASM mode) or source (SSM mode).The rendezvous point (RP) is the root of a shared tree, which is used by all sources and hosts in the PIM domain in the ASM mode. SSM does not use an RP but builds a shortest path tree (SPT) that is the lowest cost path between the source and the receiver.

When the DR determines that the last host has left a group or source, it sends a PIM prune message to remove the path from the distribution tree.

The routers forward the join or prune action hop by hop up the multicast distribution tree to create (join) or tear down (prune) the path.

Note In this publication, the terms "PIM join message" and "PIM prune message" are used to simplify the action taken when referring to the PIM join-prune message with only a join or prune action.

Join-prune messages are sent as quickly as possible by the software. You can filter the join-prune messages by defining a routing policy. For information about configuring the join-prune message policy, see the "Configuring PIM Sparse Mode" section.

You can prebuild the SPT for all known (S,G) in the routing table by triggering PIM joins upstream. To prebuild the SPT for all known (S,G)s in the routing table by triggering PIM joins upstream, even in the absence of any receivers, use the ip pim pre-build-spt command. By default, PIM (S,G) joins are triggered upstream only if the OIF-list for the (S,G) is not empty.

State Refreshes

PIM requires that multicast entries are refreshed within a 3.5-minute timeout interval. The state refresh ensures that traffic is delivered only to active listeners, and it keeps routers from using unnecessary resources.

To maintain the PIM state, the last-hop DR sends join-prune messages once per minute. State creation applies to both (*, G) and (S, G) states as follows:

If the state is not refreshed, the PIM software tears down the distribution tree by removing the forwarding paths in the multicast outgoing interface list of the upstream routers.

Rendezvous Points

A rendezvous point (RP) is a router that you select in a multicast network domain that acts as a shared root for a multicast shared tree. You can configure as many RPs as you like, and you can configure them to cover different group ranges.

BSRs

The bootstrap router (BSR) ensures that all routers in the PIM domain have the same RP cache as the BSR. You can configure the BSR to help you select an RP set from BSR candidate RPs. The function of the BSR is to broadcast the RP set to all routers in the domain. You select one or more candidate BSRs to manage the RPs in the domain. Only one candidate BSR is elected as the BSR for the domain.

Caution Do not configure both Auto-RP and BSR protocols in the same network.

Figure 4-1 shows where the BSR mechanism. router A, the software-elected BSR, sends BSR messages out all enabled interfaces (shown by the solid lines in the figure). The messages, which contain the RP set, are flooded hop by hop to all routers in the network. Routers B and C are candidate RPs that send their candidate-RP advertisements directly to the elected BSR (shown by the dashed lines in the figure).

The elected BSR receives candidate-RP messages from all the candidate RPs in the domain. The bootstrap message sent by the BSR includes information about all of the candidate RPs. Each router uses a common algorithm to select the same RP address for a given multicast group.

Figure 4-1 BSR Mechanism

In the RP selection process, the RP address with the best priority is determined by the software. If the priorities match for two or more RP addresses, the software may use the RP hash in the selection process. Only one RP address is assigned to a group.

By default, routers are not enabled to listen or forward BSR messages. You must enable the BSR listening and forwarding feature so that the BSR mechanism can dynamically inform all routers in the PIM domain of the RP set assigned to multicast group ranges.

Auto-RP

Auto-RP is a Cisco protocol that was prior to the Internet standard bootstrap router mechanism. You configure Auto-RP by selecting candidate mapping agents and RPs. Candidate RPs send their supported group range in RP-Announce messages to the Cisco RP-Announce multicast group 224.0.1.39. An Auto-RP mapping agent listens for RP-Announce messages from candidate RPs and forms a Group-to-RP mapping table. The mapping agent multicasts the Group-to-RP mapping table in RP-Discovery messages to the Cisco RP-Discovery multicast group 224.0.1.40.

Caution Do not configure both Auto-RP and BSR protocols in the same network.

Figure 4-2 shows the Auto-RP mechanism. Periodically, the RP mapping agent multicasts the RP information that it receives to the Cisco-RP-Discovery group 224.0.1.40 (shown by the solid lines in the figure).

Figure 4-2 Auto-RP Mechanism

By default, routers are not enabled to listen or forward Auto-RP messages. You must enable the Auto-RP listening and forwarding feature so that the Auto-RP mechanism can dynamically inform routers in the PIM domain of the Group-to-RP mapping.

Anycast-RP

Anycast-RP has two implementations: one uses Multicast Source Discovery Protocol (MSDP) and the other is based on RFC 4610, Anycast-RP Using Protocol Independent Multicast (PIM). This section describes how to configure PIM Anycast-RP.

You can use PIM Anycast-RP to assign a group of routers, called the Anycast-RP set, to a single RP address that is configured on multiple routers. The set of routers that you configure as Anycast-RPs is called the Anycast-RP set. This method is the only RP method that supports more than one RP per multicast group, which allows you to load balance across all RPs in the set. The Anycast RP supports all multicast groups.

PIM register messages are sent to the closest RP and PIM join-prune messages are sent in the direction of the closest RP as determined by the unicast routing protocols. If one of the RPs goes down, unicast routing ensures these message will be sent in the direction of the next-closest RP.

PIM Register Messages

PIM register messages are unicast to the RP by designated routers (DRs) that are directly connected to multicast sources. The PIM register message has the following functions:

•To notify the RP that a source is actively sending to a multicast group.

•To deliver multicast packets sent by the source to the RP for delivery down the shared tree.

The DR continues to send PIM register messages to the RP until it receives a Register-Stop message from the RP. The RP sends a Register-Stop message in either of the following cases:

•The RP has no receivers for the multicast group being transmitted.

•The RP has joined the SPT to the source but has not started receiving traffic from the source.

You can use the ip pim register-source command to configure the IP source address of register messages when the IP source address of a register message is not a uniquely routed address to which the RP can send packets. This situation might occur if the source address is filtered so that the packets sent to it are not forwarded or if the source address is not unique to the network. In these cases, the replies sent from the RP to the source address fails to reach the DR, resulting in Protocol Independent Multicast sparse mode (PIM-SM) protocol failures.

The following example shows how to configure the IP source address of the register message to the loopback 3 interface of a DR:

Designated Routers

In PIM ASM and SSM modes, the software chooses a designated router (DR) from the routers on each network segment. The DR is responsible for forwarding multicast data for specified groups and sources on that segment.

In ASM mode, the DR is responsible for unicasting PIM register packets to the RP. When a DR receives an IGMP membership report from a directly connected receiver, the shortest path is formed to the RP, which may or may not go through the DR. The result is a shared tree that connects all sources transmitting on the same multicast group to all receivers of that group.

In SSM mode, the DR triggers (*, G) or (S, G) PIM join messages toward the source. The path from the receiver to the source is determined hop by hop. The source must be known to the receiver or the DR.

Administratively Scoped IP Multicast

The administratively scoped IP multicast method allows you to set boundaries on the delivery of multicast data. For more information, see RFC 2365.

You can configure an interface as a PIM boundary so that PIM messages are not sent out that interface. For information about configuring the domain border parameter, see the "Configuring PIM Sparse Mode" section.

Virtualization Support

You can define multiple virtual routing and forwarding (VRF) instances. For each VRF, independent multicast system resources are maintained, including the MRIB.

You can use the PIM show commands with a VRF argument to provide a context for the information displayed. The default VRF is used if no VRF argument is supplied.

For information about configuring VRFs, see the Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide.

Licensing Requirements for PIM

The following table shows the licensing requirements for this feature:

Product

License Requirement

DCNM

<Feature-1> requires no license. Any feature not included in a license package is bundled with the Cisco DCNM and is provided at no charge to you. For a complete explanation of the DCNM licensing scheme, see the Cisco DCNM Licensing Guide.

DCNM

<Feature-1> requires a LAN Enterprise license. For a complete explanation of the DCNM licensing scheme and how to obtain and apply licenses, see the Cisco DCNM Licensing Guide.

Cisco NX-OS

PIM require a LAN Base Services license. For a complete explanation of the Cisco NX-OS licensing scheme and how to obtain and apply licenses, see the Cisco NX-OS Licensing Guide.

Guidelines and Limitations for PIM

PIM has the following guidelines and limitations:

•Cisco NX-OS PIM does not interoperate with any version of PIM dense mode or PIM sparse mode version 1.

•Cisco NX-OS 3000 Series switches do not support per multicast group statistics command from the show forward multicast route command.

•Do not configure both Auto-RP and BSR protocols in the same network.

•Configure candidate RP intervals to a minimum of 15 seconds.

•If a switch is configured with a BSR policy that should prevent it from being elected as the BSR, the switch ignores the policy. This behavior results in the following undesirable conditions:

–If a switch receives a BSM that is permitted by the policy, the switch, which incorrectly elected itself as the BSR, drops that BSM so that routers downstream fail to receive it. Downstream switches correctly filter the BSM from the incorrect BSR so that they do not receive RP information.

–A BSM received by a BSR from a different switch sends a new BSM but ensures that downstream switches do not receive the correct BSM.

Note If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use.

Enabling the PIM Features

Before you can access the PIM commands, you must enable the PIM feature.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license.

SUMMARY STEPS

1. configure terminal

2. feature pim

3. (Optional) show running-configuration pim

4. (Optional) copy running-config startup-config

DETAILED STEPS

Command or Action

Purpose

Step 1

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2

feature pim

Example:

switch(config)# feature pim

Enables PIM. By default, PIM is disabled.

Step 3

show running-configuration pim

Example:

switch(config)# show running-configuration pim

(Optional) Shows the running-configuration information for PIM, including the feature command.

Step 4

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring PIM Sparse Mode

You configure PIM sparse mode on every switch interface that you want to participate in a sparse mode domain. You can configure the sparse mode parameters described in Table 4-3.

Table 4-3 PIM Sparse Mode Parameters

Parameter

Description

Global to the switch

Auto-RP message action

Enables listening and forwarding of Auto-RP messages. The default is disabled, which means that the router does not listen or forward Auto-RP messages unless it is configured as a candidate RP or mapping agent.

BSR message action

Enables listening and forwarding of BSR messages. The default is disabled, which means that the router does not listen or forward BSR messages unless it is configured as a candidate RP or BSR candidate.

Register rate limit

Configures the IPv4 register rate limit in packets per second. The range is from 1 to 65,535. The default is no limit.

Initial holddown period

Configures the IPv4 initial holddown period in seconds. This holddown period is the time it takes for the MRIB to come up initially. If you want faster convergence, enter a lower value. The range is from 90 to 210. Specify 0 to disable the holddown period. The default is 210.

Per switch interface

PIM sparse mode

Enables PIM on an interface.

Designated router priority

Sets the designated router (DR) priority that is advertised in PIM hello messages on this interface. On a multi-access network with multiple PIM-enabled routers, the router with the highest DR priority is elected as the DR router. If the priorities match, the software elects the DR with the highest IP address. The DR originates PIM register messages for the directly connected multicast sources and sends PIM join messages toward the rendezvous point (RP) for directly connected receivers. Values range from 1 to 4294967295. The default is 1.

Hello authentication mode

Enables an MD5 hash authentication key, or password, in PIM hello messages on the interface so that directly connected neighbors can authenticate each other. The PIM hello messages are IPsec encoded using the Authentication Header (AH) option. You can enter an unencrypted (cleartext) key, or one of these values followed by a space and the MD5 authentication key:

•0—Specifies an unencrypted (cleartext) key

•3—Specifies a 3-DES encrypted key

•7—Specifies a Cisco Type 7 encrypted key

The authentication key can be up to 16 characters. The default is disabled.

Hello interval

Configures the interval at which hello messages are sent in milliseconds. The range is from 1 to 4294967295. The default is 30000.

Domain border

Enables the interface to be on the border of a PIM domain so that no bootstrap, candidate-RP, or Auto-RP messages are sent or received on the interface. The default is disabled.

Neighbor policy

Configures which PIM neighbors to become adjacent to based on a route-map policy1 where you can specify IP addresses to become adjacent to with the match ip address command. If the policy name does not exist, or no IP addresses are configured in a policy, then adjacency is established with all neighbors. The default is to become adjacent with all PIM neighbors.

Note We recommend that you should configure this feature only if you are an experienced network administrator.

Enters interface mode on the interface type and number, such as ethernetslot/port.

Step 9

no switchport

Example:

switch(config-if)# no switchport

Configures the interface as a Layer 3 routed interface.

Step 10

ip pim sparse-mode

Example:

switch(config-if)# ip pim sparse-mode

Enables PIM sparse mode on this interface. The default is disabled.

Step 11

ip pim dr-priority priority

Example:

switch(config-if)# ip pim dr-priority 192

(Optional) Sets the designated router (DR) priority that is advertised in PIM hello messages. Values range from 1 to 4294967295. The default is 1.

Step 12

ip pim hello-authentication ah-md5 auth-key

Example:

switch(config-if)# ip pim hello-authentication ah-md5 my_key

(Optional) Enables an MD5 hash authentication key in PIM hello messages. You can enter an unencrypted (cleartext) key or one of these values followed by a space and the MD5 authentication key:

•0—Specifies an unencrypted (cleartext) key

•3—Specifies a 3-DES encrypted key

•7—Specifies a Cisco Type 7 encrypted key

The key can be up to 16 characters. The default is disabled.

Step 13

ip pim hello-interval interval

Example:

switch(config-if)# ip pim hello-interval 25000

(Optional) Configures the interval at which hello messages are sent in milliseconds. The range is from 1 to 4294967295. The default is 30000.

Step 14

ip pim border

Example:

switch(config-if)# ip pim border

(Optional) Enables the interface to be on the border of a PIM domain so that no bootstrap, candidate-RP, or Auto-RP messages are sent or received on the interface. The default is disabled.

Step 15

ip pim neighbor-policy policy-name

Example:

switch(config-if)# ip pim neighbor-policy my_neighbor_policy

(Optional) Configures which PIM neighbors to become adjacent to based on a route-map policy with the match ip address command. The policy name can be up to 63 characters. The default is to become adjacent with all PIM neighbors.

Note We recommend that you should configure this feature only if you are an experienced network administrator.

Step 16

show ip pim interface [interface | brief] [vrfvrf-name | all]

Example:

switch(config-if)# show ip pim interface

(Optional) Displays PIM interface information.

Step 17

copy running-config startup-config

Example:

switch(config-if)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring ASM

Any Source Multicast (ASM) is a multicast distribution mode that require the use of RPs to act as a shared root between sources and receivers of multicast data.

To configure ASM mode, you configure sparse mode and the RP selection method, where you indicate the distribution mode and assign the range of multicast groups.

Configures a PIM static RP address for a multicast group range. You can specify a route-map policy name that lists the group prefixes to use with the match ipmulticast command. The default mode is ASM. The default group range is 224.0.0.0 through 239.255.255.255.

The example configures PIM ASM mode for the specified group range.

Step 3

show ip pim group-range [ip-prefix] [vrfvrf-name | all]

Example:

switch(config)# show ip pim group-range

(Optional) Displays PIM modes and group ranges.

Step 4

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring BSRs

You configure BSRs by selecting candidate BSRs and RPs.

Caution Do not configure both Auto-RP and BSR protocols in the same network.

You can configure a candidate BSR with the arguments described in Table 4-4.

Table 4-4 Candidate BSR Arguments

Argument

Description

interface

Interface type and number used to derive the BSR source IP address used in bootstrap messages.

hash-length

Hash length is the number of high order 1s used to form a mask that is ANDed with group address ranges of candidate RPs to form a hash value. The mask determines the number of consecutive addresses to assign across RPs with the same group range. For PIM, this value ranges from 0 to 32 and has a default of 30.

priority

Priority assigned to this BSR. The software elects the BSR with the highest priority, or if the BSR priorities match, the software elects the BSR with the highest IP address. This value ranges from 0, the lowest priority, to 255 and has a default of 64.

You can configure a candidate RP with the arguments described in Table 4-5.

Table 4-5 BSR Candidate RP Arguments and Keywords

Argument or Keyword

Description

interface

Interface type and number used to derive the BSR source IP address used in Bootstrap messages.

group-listip-prefix

Multicast groups handled by this RP specified in a prefix format.

interval

Number of seconds between sending candidate-RP messages. This value ranges from 1 to 65,535 and has a default of 60 seconds.

Note We recommend that you configure the candidate RP interval to a minimum of 15 seconds.

priority

Priority assigned to this RP. The software elects the RP with the highest priority for a range of groups, or if the priorities match, the highest IP address. This value ranges from 0, the highest priority, to 65,535 and has a default of 192.

Tip You should choose the candidate BSRs and candidate RPs that have good connectivity to all parts of the PIM domain.

You can configure the same router to be both a BSR and a candidate RP. In a domain with many routers, you can select multiple candidate BSRs and RPs to automatically fail over to alternates if a BSR or an RP fails.

To configure candidate BSRs and RPs, follow these steps:

Step 1 Configure whether each router in the PIM domain should listen and forward BSR messages. A router configured as either a candidate RP or a candidate BSR will automatically listen to and forward all bootstrap router protocol messages, unless an interface is configured with the domain border feature. For more information, see the "Configuring PIM Sparse Mode" section.

Step 2 Select the routers to act as candidate BSRs and RPs.

Step 3 Configure each candidate BSR and candidate RP as described in this section.

Configures a candidate bootstrap router (BSR). The source IP address used in a bootstrap message is the IP address of the interface. The hash length ranges from 0 to 32 and has a default of 30. The priority ranges from 0 to 255 and has a default of 64. For parameter details, see Table 4-4.

If you configure multiple Auto-RP mapping agents, only one is elected as the mapping agent for the domain. The elected mapping agent ensures that all candidate RP messages are sent out. All mapping agents receive the candidate RP messages and advertise the same RP cache in their RP-discovery messages.

You can configure a candidate RP with the arguments described in Table 4-7.

Table 4-7 Auto-RP Candidate RP Arguments and Keywords

Argument or Keyword

Description

interface

Interface type and number used to derive the IP address of the candidate RP used in Bootstrap messages.

group-listip-prefix

Multicast groups handled by this RP. Specified in a prefix format.

scopettl

Time-To-Live (TTL) value that represents the maximum number of hops that RP-Discovery messages are forwarded. This value can range from 1 to 255 and has a default of 32.

Step 1 For each router in the PIM domain, configure whether that router should listen and forward Auto-RP messages. A router configured as either a candidate RP or an Auto-RP mapping agent will automatically listen to and forward all Auto-RP protocol messages, unless an interface is configured with the domain border feature. For more information, see the "Configuring PIM Sparse Mode" section.

Step 2 Select the routers to act as mapping agents and candidate RPs.

Step 3 Configure each mapping agent and candidate RP as described in this section.

Configures an Auto-RP candidate RP. The default scope is 32. The default interval is 60 seconds. By default, the command creates an ASM candidate RP. For parameter details, see Table 4-7.

Note We recommend that you configure the candidate RP interval to a minimum of 15 seconds.

The example configures an ASM candidate RP.

Step 4

show ip pim group-range [ip-prefix] [vrfvrf-name | all]

Example:

switch(config)# show ip pim group-range

(Optional) Displays PIM modes and group ranges.

Step 5

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring a PIM Anycast-RP Set

To configure a PIM Anycast-RP set, follow these steps:

Step 1 Select the routers in the PIM Anycast-RP set.

Step 2 Select an IP address for the PIM Anycast-RP set.

Step 3 Configure each peer RP and local address in the PIM Anycast-RP set as described in this section.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

SUMMARY STEPS

1. configure terminal

2. interface loopback number

3. ip address ip-prefix

4. exit

5. ip pim anycast-rpanycast-rp-addressanycast-rp-peer-address

6. Repeat Step 5 using the same anycast-rp for each peer RP in the RP set

7. (Optional) show ip pim group-range [ip-prefix] [vrfvrf-name | all]

8. (Optional) copy running-config startup-config

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2

interface loopback number

Example:

switch(config)# interface loopback 0

Configures an interface loopback.

This example configures interface loopback 0.

Step 3

ip address ip-prefix

Example:

switch(config-if)# ip address 192.0.2.3/32

Configures an IP address for this interface.

This example configures an IP address for the Anycast-RP.

Step 4

exit

Example:

switch(config)# exit

Returns to configuration mode.

Step 5

ip pim anycast-rp anycast-rp-address anycast-rp-peer-address

Example:

switch(config)# ip pim anycast-rp 192.0.2.3 192.0.2.31

Configures a PIM Anycast-RP peer address for the specified Anycast-RP address. Each command with the same Anycast-RP address forms an Anycast-RP set. The IP addresses of RPs are used for communication with RPs in the set.

Step 6

Repeat Step 5 using the same Anycast-RP address for each peer RP in the Anycast-RP set.

—

Step 7

ip [autoconfig | ip-address [secondary]]

(Optional) Generates a link-local address from the link-local prefix and a modified EUI-64 format Interface Identifier, where the EUI-64 Interface Identifier is created from the relevant HSRP virtual MAC address. the ip-address...

(Optional) Virtual IP address for the virtual router (HSRP group). The IP address must be in the same subnet as the interface IP address. You must configure the virtual IP address for at least one of the routers in the HSRP group. Other routers in the group will pick up this address. The IP address can be an IPv4 address.

Step 8

show ip pim group-range [ip-prefix] [vrfvrf-name | all]

Example:

switch(config)# show ip pim group-range

(Optional) Displays PIM modes and group ranges.

Step 9

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring Shared Trees Only for ASM

You can configure shared trees only on the last-hop router for Any Source Multicast (ASM) groups, which means that the router never switches over from the shared tree to the SPT when a receiver joins an active group. You can specify a group range where the use of shared trees is to be enforced with the match ipmulticast command. This option does not affect the normal operation of the router when a source tree join-prune message is received.

The default is disabled, which means that the software can switch over to source trees.

Note In ASM mode, only the last-hop router switches from the shared tree to the SPT.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

Builds only shared trees, which means that the software never switches over from the shared tree to the SPT. You specify a route-map policy name that lists the groups to use with the match ipmulticast command. By default, the software triggers a PIM (S, G) join toward the source when it receives multicast packets for a source for which it has the (*, G) state.

Step 3

show ip pim group-range [ip-prefix] [vrfvrf-name | all]

Example:

switch(config)# show ip pim group-range

(Optional) Displays PIM modes and group ranges.

Step 4

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Setting the Maximum Number of Entries in the Multicast Routing Table

You can set the maximum number of entries in the multicast routing table (MRT).

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

SUMMARY STEPS

1. configure terminal

2. hardware profile multicast max-limitmax-entries

3. (Optional) show hardware profile status

4. (Optional) copy running-config startup-config

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2

hardware profile multicast max-limitmax-entries

Example:

switch(config)# hardware profile multicast max-limit3000

Sets the maximum number of entries in the multicast routing table.

The maximum number of entries in the multicast routing table can range from 0 to 4000.

Preventing Duplicate Packets During an RPT to SPT Switchover

Beginning with Cisco NX-OS Release 5.0(3)U1(2), you can prevent duplicate packets in the hardware when the transition from RPT to SPT is in progress.

Note When you use this command to prevent packet duplication during an RPT to SPT switchover, the switch supports source (S, G) route injections at a rate of only 500 routes every two minutes. The multicast routing table must have 500 entries free for source (S, G) routes.

SUMMARY STEPS

1. configure terminal

2. hardware profile multicast prefer-source-tree

3. (Optional) show hardware profile status

4. (Optional) copy running-config startup-config

DETAILED STEPS

Command

Purpose

Step 1

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2

hardware profile multicast prefer-source-tree

Example:

switch(config)# hardware profile multicast prefer-source-tree

Prevents duplicate packets in the hardware when the transition from RPT to SPT is in progress.

Configuring SSM

Source-Specific Multicast (SSM) is a multicast distribution mode where the software on the DR connected to a receiver that is requesting data for a multicast source builds a shortest path tree (SPT) to that source.

On an IPv4 network, a host can request multicast data for a specific source only if it is running IGMPv3 and the DR for that host is running IGMPv3. You will usually enable IGMPv3 when you configure an interface for PIM in the SSM mode. For hosts running IGMPv1 or IGMPv2, you can configure group to source mapping using SSM translation. For more information, see Chapter 3 "Configuring IGMP."

You can configure the group range that is used by SSM by specifying values on the command line. By default, the SSM group range for PIM is 232.0.0.0/8.

You can specify a route-map policy name that lists the group prefixes to use with the match ipmulticast command.

Note If you want to use the default SSM group range, you do not need to configure the SSM group range.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

Configures up to four group ranges to be treated in SSM mode. You can specify a route-map policy name that lists the group prefixes to use with the match ipmulticast command. The default range is 232.0.0.0/8. If the keyword none is specified, all group ranges are removed.

no ip pim ssm {range {ip-prefix | none} | route-mappolicy-name}

Example:

switch(config)# no ip pim ssm range none

Removes the specified prefix from the SSM range, or removes the route-map policy. If the keyword none is specified, resets the SSM range to the default of 232.0.0.0/8.

Step 3

show ip pim group-range [ip-prefix] [vrfvrf-name | all]

Example:

switch(config)# show ip pim group-range

(Optional) Displays PIM modes and group ranges.

Step 4

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring RPF Routes for Multicast

You can define RPF routes for multicast when you want multicast data to diverge from the unicast traffic path. You can define RPF routes for multicast on border routers to enable reverse path forwarding (RPF) to an external network.

Multicast routes are used not to directly forward traffic but to make RPF checks. RPF routes for multicast cannot be redistributed. For more information about multicast forwarding, see the "Multicast Forwarding" section.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

Configures an RPF route for multicast for use in RPF calculations. Route preference values range from 1 to 255. The default preferenceis 1.

Step 3

show ip static-route [vrfvrf-name]

Example:

switch(config)# show ip static-route

(Optional) Displays configured static routes.

Step 4

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Disabling Multicast Multipath

By default, the RPF interface for multicast is chosen automatically when there are multiple ECMP paths available. Disabling the automatic selection allows you to specify a single RPF interface for multicast.

Configuring Route Maps to Control RP Information Distribution

You can configure route maps to help protect against some RP configuration errors and malicious attacks. You use route maps in commands that are described in the "Configuring Message Filtering" section.

By configuring route maps, you can control distribution of RP information that is distributed throughout the network. You specify the BSRs or mapping agents to be listened to on each client router and the list of candidate RPs to be advertised (listened to) on each BSR and mapping agent to ensure that what is advertised is what you expect.

Note Only the match ipmulticast command has an effect in the route map.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

Matches the group, RP, and RP type specified. You can specify the RP type (ASM). This configuration method requires the group and RP specified as shown in the examples.

Step 4

show route-map

Example:

switch(config-route-map)# show route-map

(Optional) Displays configured route maps.

Step 5

copy running-config startup-config

Example:

switch(config-route-map)# copy running-config startup-config

(Optional) Saves configuration changes.

Configuring Message Filtering

You can configure filtering of the PIM messages described in Table 4-8.

Table 4-8 PIM Message Filtering

Message Type

Description

Global to the switch

Log Neighbor changes

Enables syslog messages that list the neighbor state changes to be generated. The default is disabled.

PIM register policy

Enables PIM register messages to be filtered based on a route-map policy1 where you can specify group or group and source addresses with the match ipmulticast command. This policy applies to routers that act as an RP. The default is disabled, which means that the software does not filter PIM register messages.

BSR candidate RP policy

Enables BSR candidate RP messages to be filtered by the router based on a route-map policy1 where you can specify the RP and group addresses, and the type ASM with the match ipmulticast command. This command can be used on routers that are eligible for BSR election. The default is no filtering of BSR messages.

BSR policy

Enables BSR messages to be filtered by the BSR client routers based on a route-map policy1 where you can specify BSR source addresses with the match ipmulticast command. This command can be used on client routers that listen to BSR messages. The default is no filtering of BSR messages.

Auto-RP candidate RP policy

Enables Auto-RP announce messages to be filtered by the Auto-RP mapping agents based on a route-map policy1 where you can specify the RP and group addresses, and the type ASM with the match ipmulticast command. This command can be used on a mapping agent. The default is no filtering of Auto-RP messages.

Auto-RP mapping agent policy

Enables Auto-RP discover messages to be filtered by client routers based on a route-map policy1 where you can specify mapping agent source addresses with the match ipmulticast command. This command can be used on client routers that listen to discover messages. The default is no filtering of Auto-RP messages.

Per switch interface

Join-prune policy

Enables join-prune messages to be filtered based on a route-map policy1 where you can specify group, group and source, or group and RP addresses with the match ipmulticast command. The default is no filtering of join-prune messages.

(Optional) Enables BSR candidate RP messages to be filtered by the router based on a route-map policy where you can specify the RP and group addresses, and the type ASM with the match ipmulticast command. This command can be used on routers that are eligible for BSR election. The default is no filtering of BSR messages.

Step 5

ip pim bsr bsr-policy policy-name

Example:

switch(config)# ip pim bsr bsr-policy my_bsr_policy

(Optional) Enables BSR messages to be filtered by the BSR client routers based on a route-map policy where you can specify BSR source addresses with the match ipmulticast command. This command can be used on client routers that listen to BSR messages. The default is no filtering of BSR messages.

(Optional) Enables Auto-RP announce messages to be filtered by the Auto-RP mapping agents based on a route-map policy where you can specify the RP and group addresses, and the type ASM with the match ipmulticast command. This command can be used on a mapping agent. The default is no filtering of Auto-RP messages.

(Optional) Enables Auto-RP discover messages to be filtered by client routers based on a route-map policy where you can specify mapping agent source addresses with the match ipmulticast command. This command can be used on client routers that listen to discover messages. The default is no filtering of Auto-RP messages.

Step 8

interface interface

Example:

switch(config)# interface ethernet 2/1

switch(config-if)#

Enters interface mode on the specified interface.

Step 9

no switchport

Example:

switch(config-if)# no switchport

Configures the interface as a Layer 3 routed interface.

Step 10

ip pim jp-policy policy-name [in|out]

Example:

switch(config-if)# ip pim jp-policy my_jp_policy

(Optional) Enables join-prune messages to be filtered based on a route-map policy where you can specify group, group and source, or group and RP addresses with the match ipmulticast command. The default is no filtering of join-prune messages.

This command filters messages in both incoming and outgoing directions.

Step 11

show run pim

Example:

switch(config-if)# show run pim

(Optional) Displays PIM configuration commands.

Step 12

copy running-config startup-config

Example:

switch(config-if)# copy running-config startup-config

(Optional) Saves configuration changes.

When routes are flushed, they are removed from the Multicast Routing Information Base (MRIB) and the Multicast Forwarding Information Base (MFIB).

When you restart PIM, the following tasks are performed:

•The PIM database is deleted.

•The MRIB and MFIB are unaffected and forwarding of traffic continues.

•The multicast route ownership is verified through the MRIB.

•Periodic PIM join and prune messages from neighbors are used to repopulate the database.

BEFORE YOU BEGIN

Ensure that you have installed the LAN Base Services license and enabled PIM.

SUMMARY STEPS

1. restart pim

2. configure terminal

3. ip pim flush-routes

4. (Optional) show running-configuration pim

5. (Optional) copy running-config startup-config

DETAILED STEPS

Command

Purpose

Step 1

restart pim

Example:

switch# restart pim

Restarts the PIM process.

Step 2

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 3

ip pim flush-routes

Example:

switch(config)# ip pim flush-routes

Removes routes when the PIM process is restarted. By default, routes are not flushed.

Step 4

show running-configuration pim

Example:

switch(config)# show running-configuration pim

(Optional) Shows the PIM running-configuration information, including the flush-routes command.

Step 5

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves configuration changes.

Verifying the PIM Configuration

To display the PIM configuration information, perform one of the following tasks:

Command

Purpose

show ip mroute {sourcegroup | group [source]} [vrfvrf-name | all]

Displays the IP multicast routing table.

show ip pim group-range [vrfvrf-name | all]

Displays the learned or configured group ranges and modes. For similar information, see also the show ip pim rp command.

show ip pim interface [interface | brief] [vrfvrf-name | all]

Displays information by the interface.

show ip pim neighbor [vrfvrf-name | all]

Displays neighbors by the interface.

show ip pim oif-list group [source] [vrfvrf-name | all]

Displays all the interfaces in the OIF-list.

show ip pim route {source group | group [source]} [vrfvrf-name | all]

Displays information for each multicast route, including interfaces on which a PIM join for that (S, G) has been received.

show ip pim rp [vrfvrf-name | all]

Displays rendezvous points (RPs) known to the software, how they were learned, and their group ranges. For similar information, see also the show ip pim group-range command.